Vacuum processing apparatus and oxidizing gas removal method

ABSTRACT

According to one aspect of the present disclosure, a vacuum processing apparatus includes: a decompressable process container; a supply port that is formed on a side wall of the process container and that is configured to supply, to the process container, an ionic liquid that absorbs an oxidizing gas; and a discharge port configured to discharge the ionic liquid supplied to the process container.

BACKGROUND 1. Technical Field

The present disclosure relates to a vacuum processing apparatus and anoxidizing gas removal method.

2. Background Art

A technique is known in which a graphene structure is formed on thesurface of a substrate housed in a process container by a remotemicrowave plasma CVD using a carbon-containing gas as a deposition rawmaterial gas (see, for example, Patent Document 1).

The present disclosure provides a technique that enables the removal ofan oxidizing gas remaining in a process container.

PRIOR ART DOCUMENT Patent Document

[Patent Document 1] Japanese Laid-open Patent Publication No. 2019-55887

SUMMARY OF THE INVENTION

According to one aspect of the present disclosure, a vacuum processingapparatus includes: a decompressable process container; a supply portthat is formed on a side wall of the process container and that isconfigured to supply, to the process container, an ionic liquid thatabsorbs an oxidizing gas; and a discharge port configured to dischargethe ionic liquid supplied to the process container.

According to the present disclosure, it is possible to remove anoxidizing gas remaining in a process container.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating an example of a vacuumprocessing apparatus according to a first embodiment;

FIG. 2 is a schematic diagram illustrating an example of a vacuumprocessing apparatus according to a second embodiment;

FIG. 3 is a schematic diagram illustrating an example of a vacuumprocessing apparatus according to a third embodiment;

FIG. 4 is a schematic diagram illustrating an example of a vacuumprocessing apparatus according to a fourth embodiment; and

FIG. 5 is an enlarged view of a joint portion between a processcontainer and a support member in the vacuum processing apparatus ofFIG. 4 .

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, non-limiting exemplary embodiments of the presentdisclosure will be described with reference to the accompanyingdrawings. In all the accompanying drawings, the same or correspondingreference numerals shall be attached to the same or correspondingcomponents and overlapping descriptions may be omitted.

[Oxidizing Gas Remaining in Process Container]

In a state in which an oxidizing gas such as H₂O gas or O₂ gas isadsorbed on the inner wall of a process container, when a substrate ishoused in the process container and a semiconductor process such asdeposition or and etching is implemented, the oxidizing gas may bedesorbed from the inner wall of the process container and may adverselyaffect the semiconductor process.

For example, as an example of a semiconductor process, in a case inwhich a graphene film is formed on the surface of a wiring layer formedon the surface of a substrate, an oxidizing gas desorbed from the innerwall of a process container oxidizes the surface of the wiring layer ofthe substrate before forming the graphene film, and an oxide film isformed at the interface between the wiring layer and the graphene film.Since the oxide formed at the interface between the wiring layer and thegraphene film has insulating properties, the contact resistance betweenthe wiring layer and the graphene film is increased.

Accordingly, the present disclosure provides a technique of supplying anionic liquid to a process container and causing an oxidizing gasremaining in the process container to be absorbed by the ionic liquid,thereby removing the oxidizing gas remaining in the process container.The details will be described below.

<Vacuum Processing Apparatus> First Embodiment

Referring to FIG. 1 , an example of a vacuum processing apparatus 1Aaccording to a first embodiment will be described. The vacuum processingapparatus 1A illustrated in FIG. 1 may be configured, for example, as aplasma processing apparatus of a RLSA (Radial Line Slot Antenna)microwave plasma system.

The vacuum processing apparatus 1A includes an apparatus body 10 and acontroller 11 that controls the apparatus body 10.

The apparatus body 10 includes a chamber 101, a stage 102, a microwaveintroduction mechanism 103, a gas supply mechanism 104, an exhaustmechanism 105, a liquid supply mechanism 106, and the like.

The chamber 101 is generally cylindrically formed. An opening 110 isformed in the substantially central portion of a bottom wall 101 a ofthe chamber 101. The bottom wall 101 a is provided with an exhaustchamber 111 that is in communication with the opening 110 and thatprotrudes downward. On a side wall 101 s of the chamber 101, atransportation port 117 is formed through which the substrate W passes.The transportation port 117 is opened and closed by a gate valve 118.The chamber 101, together with a portion of the microwave introductionmechanism 103, constitutes a process container of which the inside isdecompressable.

A substrate W to be processed is mounted on the stage 102. The stage 102has a generally disk shape. The stage 102 is made of ceramics such asaluminum nitride (AlN). The stage 102 is supported by a support post 112that has a generally cylindrical shape extending upward from thesubstantially center of the bottom of the exhaust chamber 111 and ismade of ceramics such as AlN. An edge ring 113 is provided at the outeredge of the stage 102 so as to surround the substrate W mounted on thestage 102. Inside the stage 102, a lifting/lowering pin (notillustrated) for lifting and lowering the substrate W is provided to beable to protrude/retract with respect to the upper surface of the stage102.

Inside the stage 102, a resistance heating type heater 114 is embedded.The heater 114 heats the substrate W mounted on the stage 102 inresponse to power supplied from a heater power source 115. Also, athermocouple (not illustrated) is inserted in the stage 102 to controlthe temperature of the substrate W to, for example, 350° C. to 850° C.,based on a signal from the thermocouple. In addition, within the stage102, an electrode 116 having the same size as the substrate W isembedded above the heater 114. A bias power source 119 is electricallyconnected to the electrode 116. The bias power source 119 suppliespredetermined electric power having a predetermined frequency andmagnitude to the electrode 116. This causes ions to be attracted on thesubstrate W mounted on the stage 102. It should be noted that the biaspower source 119 may not be provided depending on the characteristics ofa plasma process.

The microwave introduction mechanism 103 is provided on the uppersection of the chamber 101. The microwave introduction mechanism 103includes an antenna 121, a microwave output section 122, a microwavetransmission mechanism 123, and the like. The antenna 121 is formed witha number of slots 121 a that are through holes. The microwave outputsection 122 outputs a microwave. The microwave transmission mechanism123 directs the microwave output from the microwave output section 122to the antenna 121.

Below the antenna 121, a dielectric window 124 made of a dielectricmaterial is provided. The dielectric window 124 is supported on asupport member 132, which is annularly arranged on the upper section ofthe chamber 101. A target 140 made of metal is arranged on the lowersurface (surface facing the stage 102) of the dielectric window 124. Thetarget 140 includes, for example, at least one metal of titanium,cobalt, aluminum, yttrium, aluminum nitride, and titanium nitride. Ashielding member 125 and a wave delay plate 126 are provided on theantenna 121. A refrigerant flow path (not illustrated) is providedwithin the shielding member 125. The shielding member 125 cools theantenna 121, the dielectric window 124, the wave delay plate 126, andthe target 140 by a cooling fluid such as water flowing in therefrigerant flow path.

The antenna 121 may be formed, for example, of an aluminum plate or acopper plate having a silver or gold-plated surface. A plurality ofslots 121 a for emitting a microwave are arranged in the antenna 121 ina predetermined pattern. The arrangement pattern of the slots 121 a issuitably set so that the microwave is emitted evenly. An example of asuitable pattern may be radial line slots in which a plurality of pairsof slots 121 a including two T-shaped arranged slots 121 a as one pairare arranged concentrically. The length and array interval of the slots121 a are suitably set in accordance with the effective wavelength ofthe microwave (λg). The slots 121 a may also have other shapes, such asa circular shape or an arc shape. Further, the arrangement configurationof the slots 121 a is not particularly limited, and may be anarrangement of helical or radial other than concentric, for example. Thepattern of slots 121 a is suitably set to be microwave emissioncharacteristics that enable to obtain a desired plasma densitydistribution.

The wave delay plate 126 is made of a dielectric material having adielectric constant greater than vacuum such as quartz, ceramics(Al₂O₃), polytetrafluoroethylene, or polyimide. The wave delay plate 126has a function to make the antenna 121 smaller by shortening thewavelength of the microwave to shorter than in vacuum. It should benoted that the dielectric window 124 is made of a similar dielectricmaterial.

The thickness of the dielectric window 124 and the wave delay plate 126is adjusted so that an equivalent circuit formed by the wave delay plate126, the antenna 121, the dielectric windows 124, the target 140, andthe plasma satisfy the resonance conditions. By adjusting the thicknessof the wave delay plate 126, the phase of the microwave can be adjusted.By adjusting the thickness of the wave delay plate 126 so that the jointportion of the antenna 121 is an anti-node of a standing wave, thereflection of the microwave can be minimized and the emission energy ofthe microwave can be maximized. In addition, by making the wave delayplate 126 and the dielectric window 124 with the same material, it ispossible to prevent interfacial reflection of the microwave.

The microwave output section 122 has a microwave oscillator. Themicrowave oscillator may be of a magnetron type or of a solid statetype. The frequency of the microwave that is generated by the microwaveoscillator may be, for example, a frequency of 300 MHz to 10 GHz. As anexample, the microwave output section 122 outputs a microwave of 2.45GHz by a magnetron type microwave oscillator. The microwave is anexample of an electromagnetic wave.

The microwave transmission mechanism 123 includes a waveguide 127, acoaxial waveguide 128, a mode conversion mechanism 131, and the like.The waveguide 127 directs a microwave output from the microwave outputsection 122. The coaxial waveguide 128 includes an inner conductor 129connected to the center of the antenna 121 and an outer conductor 130.The mode conversion mechanism 131 is provided between the waveguide 127and the coaxial waveguide 128. The microwave output from the microwaveoutput section 122 propagates in the waveguide 127 in the TE mode and isconverted from the TE mode to the TEM mode by the mode conversionmechanism 131. The microwave converted to the TEM mode propagatesthrough the coaxial waveguide 128 to the wave delay plate 126 and isemitted from the wave delay plate 126 into the chamber 101 via the slots121 a of the antenna 121, the dielectric window 124, and the target 140.It should be noted that a tuner (not illustrated) is provided in themiddle of the waveguide 127 so that the impedance of the load (plasma)in the chamber 101 matches the output impedance of the microwave outputsection 122.

The gas supply mechanism 104 includes a shower ring 142. The shower ring142 is annularly arranged along the inner wall of the chamber 101. Theshower ring 142 includes an annular flow path 166 provided therein and aplurality of ejection ports 167 connected to the flow path 166 andopened therein. A gas supply section 163 is connected to the flow path166 via a pipe 161. The gas supply section 163 includes a plurality ofgas sources, a plurality of flow controllers, and the like. The gassupply section 163 is configured to supply at least one process gas froma corresponding gas source via a corresponding flow controller to theshower ring 142. The gas supplied to the shower ring 142 is suppliedinto the chamber 101 from the plurality of ejection ports 167.

In a case which a metal film is deposited on the substrate W, the gassupply section 163 supplies an inert gas controlled to a predeterminedflow rate into the chamber 101 via the shower ring 142. The inert gasmay be, for example, a noble gas or a nitrogen (N₂) gas. Alternatively,in a case in which a metal film is formed on the substrate W, the gassupply section 163 may supply, in addition to the inert gas, a reducinggas into the chamber 101 via the shower ring 142. The reducing gas maybe, for example, a hydrogen-containing gas or a halogen-containing gas.

Also, in a case in which a graphene film is deposited on the substrateW, the gas supply section 163 supplies a carbon-containing gas, ahydrogen-containing gas, and a noble gas controlled to predeterminedflow rates into the chamber 101 via the shower ring 142. Thecarbon-containing gas may be, for example, a C₂H₂ gas, a C₂H₄ gas, a CH₄gas, a C₂H₆ gas, a C₃H₈ gas, a C₃H₆ gas, or a combination thereof. Thehydrogen-containing gas may be, for example, a hydrogen (H₂) gas. Itshould be noted that a halogen-based gas such as a fluorine (F₂) gas, achlorine (Cl₂) gas, or a bromine (Br₂) gas may be used instead of or inaddition to the H₂ gas. The noble gas may be, for example, an argon (Ar)gas or a helium (He) gas.

An exhaust mechanism 105 includes an exhaust chamber 111, an exhaustpipe 181, an exhaust device 182, and the like. The exhaust pipe 181 isprovided on the side wall of the exhaust chamber 111. The exhaust device182 is connected to the exhaust pipe 181. The exhaust device 182includes a vacuum pump, a pressure control valve, and the like.

The liquid supply mechanism 106 supplies an ionic liquid into thechamber 101 and collects the ionic liquid supplied in the chamber 101.The ionic liquid is an ionic liquid that absorbs an oxidizing gas.Details of the ionic liquid that absorbs an oxidizing gas will bedescribed later. The liquid supply mechanism 106 includes a supply port191, a discharge port 192, a liquid circulating section 193, and thelike.

The supply port 191 is formed through the side wall 101 s of the chamber101. The supply port 191 supplies the ionic liquid from the side of thechamber 101 into the chamber 101. The ionic liquid supplied into thechamber 101 flows downward along the inner wall of the chamber 101, asindicated by the arrow A1 in FIG. 1 . FIG. 1 illustrates a case wherethe supply port 191 is formed below the transportation port 117.However, the supply port 191 may be formed above the transportation port117.

The discharge port 192 is formed so as to penetrate the bottom of theexhaust chamber 111. The discharge port 192 discharges the ionic liquidsupplied in the chamber 101 to the outside of the chamber 101. In FIG. 1, a case is illustrated in which the discharge port 192 is formed at thebottom of the exhaust chamber 111. It should be noted that the dischargeport 192 may be formed on the side wall of the exhaust chamber 111 or onthe bottom wall 101 a of the chamber 101. Also, a plurality of dischargeports 192 may be formed.

The liquid circulating section 193 collects the ionic liquid dischargedfrom the discharge port 192 and introduces the collected ionic liquidinto the supply port 191 to circulate the ionic liquid. The liquidcirculating section 193 includes a tank 193 a, a temperature controlmechanism 193 b, a forward pipe 193 c, a return pipe 193 d, and thelike.

The tank 193 a is connected to the discharge port 192 via the returnpipe 193 d. The tank 193 a stores the ionic liquid that is dischargedfrom the discharge port 192.

Temperature control mechanism 193 b includes a heater, a temperaturesensor (neither illustrated), and the like. The temperature controlmechanism 193 b controls the temperature of the ionic liquid in the tank193 a by controlling the heater based on the detected value of thetemperature sensor.

The forward pipe 193 c connects the supply port 191 to the tank 193 a.The forward pipe 193 c introduces the ionic liquid stored in the tank193 a into the supply port 191. A valve 193 e is interposed on theforward pipe 193 c. When the valve 193 e is opened, the ionic liquid isintroduced from within the tank 193 a into the supply port 191, and whenthe valve 193 e is closed, the introduction of the ionic liquid fromwithin the tank 193 a into the supply port 191 is stopped.

The return pipe 193 d connects the discharge port 192 to the tank 193 a.The return pipe 193 d collects the ionic liquid discharged from thedischarge port 192 into the tank 193 a. A valve 193 f is interposed onthe return pipe 193 d. When the valve 193 f is opened, the ionic liquidis collected from the discharge port 192 into the tank 193 a, and whenthe valve 193 f is closed, the collection of the ionic liquid from thetank 193 a into the supply port 191 is stopped.

The controller 11 includes a memory, a processor, an input/outputinterface, and the like. The memory contains a recipe including aprogram executed by the processor and the conditions of each process.The processor executes a program read from the memory and controls eachsection of the apparatus body 10 through the input/output input/outputinterface based on the recipe stored in the memory.

For example, the controller 11 performs a method of removing oxidizinggas prior to carrying out a semiconductor process in a process containerhousing a substrate. Specifically, the controller 11 controls to openthe valves 193 e and 193 f prior to the semiconductor process. Thiscauses the ionic liquid to be supplied from the supply port 191 into thechamber 101, and the supplied ionic liquid absorbs the oxidizing gasremaining in the chamber 101. The ionic liquid absorbing the oxidizinggas is discharged out of the chamber 101 through the discharge port 192.It should be noted that the controller 11 may perform the method ofremoving the oxidizing gas at a different timing from that beforeperforming the semiconductor process.

As described above, the vacuum processing apparatus 1A according to thefirst embodiment includes the supply port 191 formed on the side wall101 s of the chamber 101 to supply the ionic liquid into the chamber 101and the discharge port 192 for discharging the ionic liquid supplied inthe chamber 101. This allows the ionic liquid to be supplied from thesupply port 191 into the chamber 101 to absorb the oxidizing gasremaining in the chamber 101 by the ionic liquid. In addition, the ionicliquid absorbing the oxidizing gas can be discharged from the dischargeport 192 to the chamber 101. As a result, the oxidizing gas remaining inthe chamber 101 can be removed.

It should be noted that although a case has been described in the firstembodiment in which one supply port 191 is formed, the presentdisclosure is not limited to this. For example, a plurality of supplyports 191 may be formed. In a case in which a plurality of supply ports191 are formed, the plurality of supply ports 191 are preferably formedat intervals along the circumferential direction of the side walls 101 sof the chamber 101. This enables the ionic liquid to be ejected from theplurality of positions in the circumferential direction of the chamber101. Therefore, the ionic liquid flows over a wide range of inner wallof the chamber 101, and the surface area of the ionic liquid flowing inthe chamber 101 becomes large. As a result, the absorption efficiency ofthe oxidizing gas remaining in the chamber 101 is increased.

Second Embodiment

Referring to FIG. 2 , an example of a vacuum processing apparatus 1Baccording to a second embodiment will be described. The vacuumprocessing apparatus 1B according to the second embodiment differs fromthe vacuum processing apparatus 1A according to the first embodiment inthat a groove 101 g is formed on the inner wall of the chamber 101 toflow the ionic liquid along the circumferential direction of the innerwall. Hereinafter, different points from the vacuum processing apparatus1A will be mainly described.

The groove 101 g is spirally formed along the circumferential directionof the inner wall of the chamber 101. The upper side end of the groove101 g communicates with the supply port 191 to allow the ionic liquidsupplied from the supply port 191 to flow along the circumferentialdirection of the inner wall of the chamber 101. Therefore, because theionic liquid flows over a wide range of inner wall of the chamber 101,the surface area of the ionic liquid flowing in the chamber 101 becomeslarge. As a result, the absorption efficiency of the oxidizing gasremaining in the chamber 101 is increased.

As described above, the vacuum processing apparatus 1B according to thesecond embodiment includes the supply port 191 formed in the side wall101 s of the chamber 101 to supply the ionic liquid into the chamber 101and the discharge port 192 for discharging the ionic liquid suppliedinto the chamber 101. This allows the ionic liquid to be supplied fromthe supply port 191 into the chamber 101 to absorb the oxidizing gasremaining in the chamber 101 by the ionic liquid. In addition, the ionicliquid absorbing the oxidizing gas can be discharged from the dischargeport 192 to the chamber 101. As a result, the oxidizing gas remaining inthe chamber 101 can be removed.

Further, according to the vacuum processing apparatus 1B according tothe second embodiment, the groove 101 g for flowing the ionic liquidalong the circumferential direction of the inner wall is formed on theinner wall of the chamber 101. This causes the ionic liquid to flowalong the groove 101 g within the chamber 101. Therefore, the ionicliquid flows over a wide range of inner wall of the chamber 101, and thesurface area of the ionic liquid flowing in the chamber 101 becomeslarge. Also, because the path from the supply port 191 to the dischargeport 192 becomes long, the time for the ionic liquid to flow in thechamber 101 becomes long. As a result, the absorption efficiency of theoxidizing gas remaining in the chamber 101 is increased.

It should be noted that although a case has been described in the secondembodiment in which one supply port 191 is formed, the presentdisclosure is not limited to this. For example, a plurality of supplyports 191 may be formed. In a case in which a plurality of supply ports191 are formed, it is preferable that the plurality of supply ports 191are formed at intervals along the circumferential direction of the sidewall 101 s of the chamber 101, and that a groove 101 g is formedcorresponding to each of the plurality of supply ports 191. Therefore,because the ionic liquid flows over a wide range of inner wall of thechamber 101, the surface area of the ionic liquid flowing in the chamber101 becomes large. As a result, the absorption efficiency of theoxidizing gas remaining in the chamber 101 is increased.

Third Embodiment

Referring to FIG. 3 , an example of a vacuum processing apparatus 1Caccording to a third embodiment will be described. The vacuum processingapparatus 1C according to the third embodiment differs from the vacuumprocessing apparatus 1A of the first embodiment in including a liquidsupply mechanism 306 including a supply port 391 provided annularlyalong the inner wall of the chamber 101 instead of the supply port 191.Hereinafter, different points from the vacuum processing apparatus 1Awill be mainly described.

The liquid supply mechanism 306 supplies an ionic liquid into thechamber 301 and collects the ionic liquid supplied into the chamber 301.The ionic liquid is an ionic liquid that absorbs an oxidizing gas. Theliquid supply mechanism 306 includes the supply port 391, the dischargeport 192, the liquid circulating section 193, and the like.

The supply port 391 is provided annularly along the inner wall of thechamber 101. The supply port 391 includes an annular liquid flow path391 a provided inside and a plurality of liquid ejection ports 391 bconnected to and opened inside the liquid flow path 391 a. The tank 193a is connected to the liquid flow path 391 a through the forward pipe193 c. While flowing in the circumferential direction of the chamber 101along the liquid flow path 391 a, the ionic liquid introduced to thesupply port 391 is supplied from the plurality of liquid ejection ports391 b into the chamber 101 as indicated by the arrow A3 in FIG. 3 andflows downward along the inner wall of the chamber 101. Therefore,because the ionic liquid flows over a wide range of inner wall of thechamber 101, the surface area of the ionic liquid flowing in the chamber101 becomes large. As a result, the absorption efficiency of theoxidizing gas remaining in the chamber 101 is increased.

As described above, the vacuum processing apparatus 1C according to thethird embodiment includes the supply port 391 formed on the side wall101 s of the chamber 101 to supply the ionic liquid into the chamber 101and the discharge port 192 for discharging the ionic liquid supplied inthe chamber 101. This allows the ionic liquid to be supplied from thesupply port 391 into the chamber 101 to absorb the oxidizing gasremaining in the chamber 101 by the ionic liquid. In addition, the ionicliquid absorbing the oxidizing gas can be discharged from the dischargeport 192 to the chamber 101.

Also, according to the vacuum processing apparatus 1C of the thirdembodiment, the supply port 391 includes the annular liquid flow path391 a provided inside and the plurality of liquid ejection ports 391 bconnected to and opened inside the liquid flow path 391 a. As a result,the ionic liquid can be ejected from the plurality of positions in thecircumferential direction of the chamber 101. Therefore, the ionicliquid flows over a wide range of inner wall of the chamber 101, and thesurface area of the ionic liquid flowing in the chamber 101 becomeslarge. As a result, the absorption efficiency of the oxidizing gasremaining in the chamber 101 is increased.

It should be noted that although, in the third embodiment describedabove, the vacuum processing apparatus 1C includes the liquid supplymechanism 306 including the supply port 391 provided in an annular shapealong the inner wall of the chamber 101 in lieu of the supply port 191included in the vacuum processing apparatus 1A, the present disclosureis not limited to this. For example, the vacuum processing apparatus 1Cmay include both a supply port 191 and a supply port 391.

Fourth Embodiment

An example of a vacuum processing apparatus 1D according to a fourthembodiment will be described with reference to FIG. 4 and FIG. 5 . Thevacuum processing apparatus 1D according to the fourth embodimentdiffers from the vacuum processing apparatus 1A according to the firstembodiment in that a recess 101 h for flowing an ionic liquid is formedat a joint portion between the members constituting the processcontainer. Hereinafter, different points from the vacuum processingapparatus 1A will be mainly described.

A sealing material 151 is provided at the joint portion of the chamber101 and a support member 132 to seal the joint portion. The sealingmaterial 151 may be, for example, an O-ring.

The recess 101 h is annularly formed along the sealing material 151 onthe vacuum side of the sealing material 151 at the joint portion of thechamber 101 and the support member 132. The recess 101 h is incommunication with the supply port 491, and the ionic liquid is suppliedto the recess 101 h through the supply port 491. The ionic liquidsupplied to the recess 101 h flows along the circumferential directionof the chamber 101 along the recess 101 h.

The recess 101 h is preferably formed so that the ionic liquid flowingthrough the recess 101 h contacts both the chamber 101 and the supportmember 132. This allows the ionic liquid flowing through the recess 101h to function as an annular conductive sealing material represented by aspiral seal. That is, the ionic liquid flowing through the recess 101 hensures continuity between the chamber 101 and the support member 132and keeps the support member 132 at the ground potential. The ionicliquid flowing through the recess 101 h also prevents the leakage ofhigh frequency or plasma from between the chamber 101 and the supportmember 132. It should be noted that in a case in which the ionic liquidflowing in the recess 101 h is used instead of a spiral seal, the ionicliquid flowing in the recess 101 h is recovered by opening the valve 193f when the chamber 101 is opened to atmosphere by maintenance or thelike. Further, when the maintenance or the like is completed and theinside of the chamber 101 is depressurized, the valve 193 f is closedand the valve 193 e is opened to fill the recess 101 h with the ionicliquid and then the inside of the chamber 101 is depressurized. Thus,since the ionic liquid filled in the recess 101 h absorbs the oxidizinggas within the chamber 101, the chamber 101 can be allowed to be in ahigh vacuum and an environment with less oxidizing gas can be formed.

The recess 101 h has a depth on the vacuum side deeper than the depth onthe sealing material 151 side, as illustrated in FIG. 5 . Thus, theionic liquid filled in the recess 101 h is suppressed from flowing outto the vacuum side, and therefore the state in which the recess 101 h isfilled with the ionic liquid can be maintained.

The supply port 491 is formed so as to penetrate the support member 132.The supply port 491 is in communication with the recess 101 h andsupplies the ionic liquid from the side of the process container to therecess 101 h in the process container.

The discharge port 492 is formed to penetrate the side wall 101 s of thechamber 101 and is in communication with the recess 101 h. The dischargeport 492 discharges the ionic liquid flowing through the recess 101 h tothe outside of the chamber 101.

As described above, the vacuum processing apparatus 1D according to thefourth embodiment includes the supply port 491 formed on the side wall(support member 132) of the process container to supply the ionic liquidto the recess 101 h and the discharge port 492 that discharges the ionicliquid supplied to the recess 101 h. This allows the ionic liquid to besupplied from the supply port 491 to the recess 101 h to absorb theoxidizing gas remaining in the chamber 101 by the ionic liquid. Inaddition, the ionic liquid absorbing the oxidizing gas can be dischargedfrom the discharge port 492 to the chamber 101. As a result, theoxidizing gas remaining in the chamber 101 can be removed.

In addition, according to the vacuum processing apparatus 1D of thefourth embodiment, the ionic liquid flowing through the recess 101 hcontacts both the chamber 101 and the support member 132. This allowsthe ionic liquid flowing through the recess 101 h to function as anannular conductive sealing material instead of a spiral seal. That is,the ionic liquid flowing through the recess 101 h ensures continuitybetween the chamber 101 and the support member 132 and keeps the supportmember 132 at the ground potential. The ionic liquid flowing through therecess 101 h also prevents the leakage of high frequency or plasma frombetween the chamber 101 and the support member 132.

It should be noted that although the depth on the vacuum side is deeperthan the depth on the sealing material 151 side of the recess 101 h inthe described fourth embodiment, the present disclosure is not limitedthereto. For example, the depth of the vacuum side and the depth of thesealing material 151 side of the recess 101 h may be the same. In thiscase, a portion of the ionic liquid flowing through the recess 101 hflows into the inner wall of the chamber 101, thereby increasing thesurface area of the ionic liquid flowing through the chamber 101. As aresult, the absorption efficiency of the oxidizing gas remaining in thechamber 101 is increased. In this case, in addition to the dischargeport 492 communicating with the recess 101 h, by providing a dischargeport formed to penetrate the bottom of the exhaust chamber 111, theionic liquid flowing into the inner wall of the chamber 101 can bedischarged to the outside of the chamber 101.

Although, in the fourth embodiment described above, the vacuumprocessing apparatus 1D includes the liquid supply mechanism 406including the supply port 491 formed to penetrate the support member 132instead of the supply port 191 included in the vacuum processingapparatus 1A, the present disclosure is not limited to this. Forexample, the vacuum processing apparatus 1D may include both the supplyport 191 and the supply port 491. For example, the vacuum processingapparatus 1D may include the groove 101 g included in the vacuumprocessing apparatus 1B and may include the supply port 391 included inthe vacuum processing apparatus 1C.

[Ionic Liquid]

In the vacuum processing apparatuses 1A to 1D, an example of a suitablyavailable ionic liquid will be described. The ionic liquid is an ionicliquid that absorbs an oxidizing gas. Examples of the oxidizing gasinclude H₂O gas and O₂ gas.

In a case in which the oxidizing gas to be absorbed by the ionic liquidis H₂O gas, the ionic liquid having a molecular structure with a highpolarity can be suitably used as the ionic liquid. By using the ionicliquid having a molecular structure with a high polarity, the ionicliquid can efficiently absorb H₂O, which is a polar molecule. Examplesof such an ionic liquid include DEME-BF₄(N,N-Diethyl-N-methyl-N-(2-methoxyethyl)ammonium tetrafluoroborate) andEMI-AcO (1-Ethyl-3-methylimidazolium-acetate). Also, it may be ahalide-based ionic liquid such as [BPy]Cl represented by chemicalformula I1, [B2MPY]Cl represented by chemical formula I2, [B3MPy]Clrepresented by chemical formula I3, and [B4MPY]Cl represented bychemical formula I4.

Chemical Formulas 1

In a case in which the oxidizing gas to be absorbed by the ionic liquidis H₂O gas and O₂ gas, the ionic liquid having a molecular structureincluding a non-polar portion can be preferably used as the ionicliquid, for example. In general, because many ionic liquids, which arecombinations of anions and cations, have polarity, it is considered thatnonpolar O₂ molecules are not easily absorbed by an ionic liquid withpolarity. Therefore, by using ionic liquid having a molecular structureincluding a non-polar portion, O₂ gas can be absorbed efficiently by thenonpolar portion contained in the ionic liquid. Such an ionic liquid maybe MEMP(N-(2-methoxyethyl)-N-methyl-pyrrolidinium)-TFSI (bis(tri-fluoro-methane-sulfonyl) imide)

The embodiments disclosed herein should be considered exemplary in allrespects and are not limited thereto. The embodiments as described abovemay be, omitted, substituted, and changed in various forms withoutdeparting from the appended claims and spirit thereof.

In the above embodiments, although a case has been described in which aliquid circulating section for introducing and circulating an ionicliquid discharged from a discharge port to a supply port, the presentdisclosure is not limited thereto. For example, an ionic liquid may beintroduced from an ionic liquid supply source into a supply port withoutproviding a liquid circulation section.

In the embodiments described above, the vacuum processing apparatus isconfigured as a cold wall type apparatus, but the present disclosure isnot limited thereto. The ionic liquid does not volatilize even in vacuumand has heat resistance. Thus, the vacuum processing apparatus may be ahot wall type apparatus in which the wall surface of the processcontainer is heated to a high temperature.

In the embodiments described above, the vacuum processing apparatus isconfigured as a plasma processing apparatus, but the present disclosureis not limited thereto. The vacuum processing apparatus is not limitedto a plasma processing apparatus as long as it is an apparatus thatapplies a predetermined process (e.g., deposition, etching) to asubstrate. For example, the vacuum processing apparatus may be an ALD(Atomic Layer Deposition) apparatus, a CVD (Chemical Vapor Deposition)apparatus, a PVD (Physical Vapor Deposition) apparatus, or the like.

DESCRIPTION OF THE REFERENCE NUMERALS

1A to 1D vacuum processing apparatus

101 Chamber

191, 391, 491 supplying port

192, 492 discharge port

What is claimed is:
 1. A vacuum processing apparatus comprising: adecompressable process container; a supply port that is formed on a sidewall of the process container and that is configured to supply, to theprocess container, an ionic liquid that absorbs an oxidizing gas; and adischarge port configured to discharge the ionic liquid supplied to theprocess container.
 2. The vacuum processing apparatus according to claim1, wherein the ionic liquid is supplied from the supply port to an innerwall of the process container.
 3. The vacuum processing apparatusaccording to claim 2, wherein a spiral groove for flowing the ionicliquid is formed on the inner wall of the process container.
 4. Thevacuum processing apparatus according to claim 1, wherein the supplyport includes: an annular liquid flow path provided along acircumferential direction of the process container; and a plurality ofliquid ejection ports connected to the liquid flow path and openedinside the process container.
 5. The vacuum processing apparatusaccording to claim 1, wherein the discharge port is provided so as topenetrate a bottom of the process container.
 6. The vacuum processingapparatus according to claim 1, further comprising: a sealing materialconfigured to seal a joint portion between members constituting theprocess container; and a recess that is provided on a vacuum side of thesealing material at the joint portion and that is in communication withthe supply port and for flowing the ionic liquid supplied from thesupply port along the sealing material.
 7. The vacuum processingapparatus according to claim 6, wherein the discharge port is providedin communication with the recess.
 8. The vacuum processing apparatusaccording to claim 6, wherein the ionic liquid flowing through therecess is in contact with both of the members constituting the processcontainer.
 9. The vacuum processing apparatus according to claim 1,further comprising: a valve configured to stop discharge of the ionicliquid from the discharge port.
 10. The vacuum processing apparatusaccording to claim 1, wherein the oxidizing gas contains H₂O gas. 11.The vacuum processing apparatus according to claim 1, furthercomprising: a liquid circulating section configured to introduce theionic liquid discharged from the discharge port to the supply port andcirculate the ionic liquid.
 12. The vacuum processing apparatusaccording to claim 1, wherein the liquid circulating section includes atank configured to store the ionic liquid discharged from the dischargeport; and a temperature control mechanism configured to control atemperature of the ionic liquid in the tank.
 13. The vacuum processingapparatus according to claim 1, wherein a process of depositing agraphene film is performed in the process container.
 14. A method forremoving an oxidizing gas, the method comprising: suppling an ionicliquid that absorbs an oxidizing gas from a supply port formed on a sidewall of a decompressable process container to the process container,thereby absorbing the oxidizing gas remaining in the process containerby the ionic liquid; and discharging the ionic liquid supplied to theprocess container.